Elastomeric compounds incorporating silicon-treated carbon blacks

ABSTRACT

Disclosed are elastomeric compounds including an elastomer and a silicon-treated carbon black, and optionally including a coupling agent. The elastomeric compound exhibits poorer abrasion resistance in the absence of a coupling agent, lower hysteresis at high temperature and comparable or increased hysteresis at low temperature compared to an elastomer containing an untreated carbon black. A variety of elastomers and formulations employing such elastomers are contemplated and disclosed. Elastomeric compounds incorporating an elastomer and an oxidized, silicon-treated carbon black are also disclosed. Also disclosed are methods for preparing elastomers compounded with the treated carbon black.

This application is a continuation of 08/750,017, filed Aug. 14,1997,now U.S. Pat. No. 6,028,137; which was a continuation-in-part of priorU.S. application No. 08/446,141 filed May 22, 1995, now U.S. Pat. No.5,830,930; U.S. Pat. application No. 08/446,142 filed May 22, 1995, nowU.S. Pat. No. 5,877,238; and U.S. Pat. application No. 08/528,895 filedSep. 15, 1995, now abandoned; and is the national phase application ofPCT/US96/07310 filed May 21, 1996.

FIELD OF THE INVENTION

The present invention relates to novel elastomeric compounds exhibitingimproved hysteresis properties. More particularly, the invention relatesto novel elastomeric compounds incorporating silicon-treated carbonblacks and products manufactured from such compounds.

BACKGROUND OF THE INVENTION

Carbon blacks are widely used as pigments, fillers and reinforcingagents in the compounding and preparation of rubber and otherelastomeric compounds. Carbon blacks are particularly useful asreinforcing agents in the preparation of elastomeric compounds used inthe manufacture of tires.

Carbon blacks are generally produced in a furnace-type reactor bypyrolyzing a hydrocarbon feedstock with hot combustion gases to producecombustion products containing particulate carbon black. Carbon blackexists in the form of aggregates. The aggregates, in turn are formed ofcarbon black particles. However, carbon black particles do not generallyexist independently of the carbon black aggregate. Carbon blacks aregenerally characterized on the basis of analytical properties,including, but not limited to particle size and specific surface area;aggregate size, shape, and distribution; and chemical and physicalproperties of the surface. The properties of carbon blacks areanalytically determined by tests known to the art. For example, nitrogenadsorption surface area (measured by ASTM test procedure D3037-Method A)and cetyl-trimethyl ammonium bromide adsorption value (CTAB) (measuredby ASTM test procedure D3765 [09.01]), are measures of specific surfacearea. Dibutylphthalate absorption of the crushed (CDBP) (measured byASTM test procedure D3493-86) and uncrushed (DBP) carbon black (measuredby ASTM test procedure D2414-93), relates to the aggregate structure.The bound rubber value relates to the surface activity of the carbonblack. The properties of a given carbon black depend upon the conditionsof manufacture and may be modified, e.g., by altering temperature,pressure, feedstock, residence time, quench temperature, throughput, andother parameters.

It is generally desirable in the production of tires to employ carbonblack-containing compounds when constructing the tread and otherportions of the tire. For example, a suitable tread compound will employan elastomer compounded to provide high abrasion resistance and goodhysteresis balance at different temperatures. A tire having highabrasion resistance is desirable because abrasion resistance isproportional to tire life. The physical properties of the carbon blackdirectly influence the abrasion resistance and hysteresis of the treadcompound. Generally, a carbon black with a high surface area and smallparticle size will impart a high abrasion resistance and high hysteresisto the tread compound. Carbon black loading also affects the abrasionresistance of the elastomeric compounds. Abrasion resistance increaseswith increased loading, at least to an optimum point, beyond whichabrasion resistance actually decreases.

The hysteresis of an elastomeric compound relates to the energydissipated under cyclic deformation. In other words, the hysteresis ofan elastomeric composition relates to the difference between the energyapplied to deform the elastomeric composition and the energy released asthe elastomeric composition recovers to its initial undeformed state.Hysteresis is characterized by a loss tangent, tan 8, which is a ratioof the loss modulus to the storage modulus (that is, viscous modulus toelastic modulus). Tires made with a tire tread compound having a lowerhysteresis measured at higher temperatures, such as 40° C. or higher,will have reduced rolling resistance, which in turn, results in reducedfuel consumption by the vehicle using the tire. At the same time, a tiretread with a higher hysteresis value measured at low temperature, suchas 0° C. or lower, will result in a tire with high wet traction and skidresistance which will increase driving safety. Thus, a tire treadcompound demonstrating low hysteresis at high temperatures and highhysteresis at low temperatures can be said to have a good hysteresisbalance.

There are many other applications where it is useful to provide anelastomer exhibiting a good hysteresis balance but where the abrasionresistance is not an important factor. Such applications include but arenot limited to tire components such as undertread, wedge compounds,sidewall, carcass, apex, bead filler and wire skim; engine mounts; andbase compounds used in industrial drive and automotive belts.

Silica is also used as a reinforcing agent (or filler) for elastomers.However, using silica alone as a reinforcing agent for elastomer leadsto poor performance compared to the results obtained with carbon blackalone as the reinforcing agent. It is theorized that strongfiller-filler interaction and poor filler-elastomer interaction accountsfor the poor performance of silica. The silica-elastomer interaction canbe improved by chemically bonding the two with a chemical couplingagent, such as bis (3-triethoxysilylpropyl) tetrasulfane, commerciallyavailable as Si-69 from Degussa AG, Germany. Coupling agents such asSi-69 create a chemical linkage between the elastomer and the silica,thereby coupling the silica to the elastomer.

When the silica is chemically coupled to the elastomer, certainperformance characteristics of the resulting elastomeric composition areenhanced. When incorporated into vehicle tires, such elastomericcompounds provide improved hysteresis balance. However, elastomercompounds containing silica as the primary reinforcing agent exhibit lowthermal conductivity, high electrical resistivity, high density and poorprocessability.

When carbon black alone is used as a reinforcing agent in elastomericcompositions, it does not chemically couple to the elastomer but thecarbon black surface provides many sites for interacting with theelastomer. While the use of a coupling agent with carbon black mightprovide some improvement in performance to an elastomeric composition,the improvement is not comparable to that obtained when using a couplingagent with silica.

It is an object of the present invention to provide novel elastomericcompounds exhibiting improved hysteresis balance. It is another objectto provide an elastomeric compound incorporating silicon-treated carbonblacks. It is yet another object of the present invention to provide anelastomeric compound incorporating silicon-treated carbon blacks,wherein the carbon black may be efficiently coupled to the elastomerwith a coupling agent. Such a carbon black may be employed for example,in tire compounds, industrial rubber products and other rubber goods. Itis a further object of the present invention to provide silicon-treatedcarbon black/elastomeric formulations using a variety of elastomersuseful in a variety of product applications. Other objects of thepresent invention will become apparent from the following descriptionand claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a portion of one type of carbon blackreactor which may be used to produce the treated carbon blacks of thepresent invention.

FIG. 2 is a graph demonstrating the results of a bound rubber testcarried out on elastomeric compositions of the present invention.

FIGS. 3a, 3 b and 3 c are graphs demonstrating hysteresis valuesmeasured at different temperatures and strains on elastomericcompositions of the present invention.

FIGS. 4a- 4 d are photomicrographs comparing carbon blacks useful in thepresent invention and prior art carbon blacks.

SUMMARY OF THE INVENTION

The present invention is directed to an elastomeric compound includingan elastomer and a silicon-treated carbon black, and optionallyincluding a coupling agent. A variety of elastomers and formulationsemploying such elastomers are contemplated and disclosed. Thesilicon-treated carbon black imparts to the elastomer poorer abrasionresistance, lower hysteresis at high temperature and comparable orincreased hysteresis at low temperature compared to an untreated carbonblack. Elastomeric compounds incorporating an elastomer and an oxidized,silicon-treated carbon black are also disclosed. Also disclosed aremethods for preparing elastomeric compounds with the silicon-treatedcarbon blacks and products manufactured from such compounds.

DETAILED DESCRIPTION OF THE INVENTION

The present inventors have discovered that elastomeric compounds havingdesirable hysteresis and other properties may be obtained by compoundingan elastomer with a silicon-treated carbon black. In the silicon-treatedcarbon black a silicon-containing species, including but not limited to,oxides and carbides of silicon, may be distributed through at least aportion of the carbon black aggregate as an intrinsic part of the carbonblack.

In an elastomeric compound including an elastomer and a silicon-treatedcarbon black, the silicon-treated carbon black imparts to the elastomerpoorer abrasion resistance, comparable or higher loss tangent at lowtemperature and a lower loss tangent at high temperature, compared to anuntreated carbon black.

Silicon-treated carbon black aggregates do not represent a mixture ofdiscrete carbon black aggregates and discrete silica aggregates. Rather,the silicon-treated carbon black aggregates of the present inventioninclude at least one silicon-containing region either at the surface ofor within the carbon black aggregate.

When the silicon-treated carbon black is examined under STEM-EDX, thesilicon signal corresponding to the silicon-containing species is foundto be present in individual carbon black aggregates. By comparison, forexample, in a physical mixture of silica and carbon black, STEM-EDXexamination reveals distinctly separate silica and carbon blackaggregates.

The silicon-treated carbon blacks may be obtained by manufacturing thecarbon black in the presence of volatizable silicon-containingcompounds. Such carbon blacks are preferably produced in a modular or“staged,” furnace carbon black reactor as depicted in FIG. 1. Thefurnace carbon black reactor has a combustion zone 1, with a zone ofconverging diameter 2; a feedstock injection zone with restricteddiameter 3; and a reaction zone 4.

To produce carbon blacks with the reactor described above, hotcombustion gases are generated in combustion zone 1 by contacting aliquid or gaseous fuel with a suitable oxidant stream such as air,oxygen, or mixtures of air and oxygen. Among the fuels suitable for usein contacting the oxidant stream in combustion zone 1, to generate thehot combustion gases, are included any readily combustible gas, vapor orliquid streams such as natural gas, hydrogen, methane, acetylene,alcohols, or kerosene. It is generally preferred, however, to use fuelshaving a high content of carbon-containing components and in particular,hydrocarbons. The ratio of air to fuel varies with the type of fuelutilized. When natural gas is used to produce the carbon blacks of thepresent invention, the ratio of air to fuel may be from about 10:1 toabout 1000:1. To facilitate the generation of hot combustion gases, theoxidant stream may be pre-heated.

The hot combustion gas stream flows downstream from zones 1 and 2 intozones 3 and 4. The direction of the flow of hot combustion gases isshown in FIG. 1 by the arrow. Carbon black feedstock, 6, is introducedat point 7 into the feedstock injection zone 3. The feedstock isinjected into the gas stream through nozzles designed for optimaldistribution of the oil in the gas stream. Such nozzles may be eithersingle or bi-fluid. Bi-fluid nozzles may use steam or air to atomize thefuel. Single-fluid nozzles may be pressure atomized or the feedstock canbe directly injected into the gas-stream. In the latter instance,atomization occurs by the force of the gas-stream.

Carbon blacks can be produced by the pyrolysis or partial combustion ofany liquid or gaseous hydrocarbon. Preferred carbon black feedstocksinclude petroleum refinery sources such as decanted oils from catalyticcracking operations, as well as the by-products from coking operationsand olefin manufacturing operations.

The mixture of carbon black-yielding feedstock and hot combustion gasesflows downstream through zone 3 and 4. In the reaction zone portion ofthe reactor, the feedstock is pyrolyzed to carbon black. The reaction isarrested in the quench zone of the reactor. Quench 8 is locateddownstream of the reaction zone and sprays a quenching fluid, generallywater, into the stream of newly formed carbon black particles. Thequench serves to cool the carbon black particles and to reduce thetemperature of the gaseous stream and decrease the reaction rate. Q isthe distance from the beginning of reaction zone 4 to quench point 8,and will vary according to the position of the quench. Optionally,quenching may be staged, or take place at several points in the reactor.

After the carbon black is quenched, the cooled gases and carbon blackpass downstream into any conventional cooling and separating meanswhereby the carbon black is recovered. The separation of the carbonblack from the gas stream is readily accomplished by conventional meanssuch as a precipitator, cyclone separator, bag filter or other meansknown to those skilled in the art. After the carbon black has beenseparated from the gas stream, it is optionally subjected to apelletization step.

The silicon treated carbon blacks of the present invention may be madeby introducing a volatilizable silicon containing compound into thecarbon black reactor at a point upstream of the quench zone. Usefulvolatilizable compounds include any compound, which is volatilizable atcarbon black reactor temperatures. Examples include, but are not limitedto, silicates such as tetraethoxy orthosilicate (TEOS) and tetramethoxyorthosilicate, silanes such as, tetrachloro silane, and trichloromethylsilane; and volatile silicone polymers such asoctamethylcyclotetrasiloxane (OMTS). The flow rate of the volatilizablecompound will determine the weight percent of silicon in the treatedcarbon black. The weight percent of silicon in the treated carbon blackshould range from about 0.1% to 25%, and preferably about 0.5% to about10%, and most preferably about 2% to about 6%. It has been found thatinjecting silicon containing compound into the carbon black reactorresults in an increase in the structure (e.g., CDBP) of the product.This is desirable in many applications of carbon black.

The volatilizable compound may be premixed with the carbon black-formingfeedstock and introduced with the feedstock into the reaction zone.Alternatively, the volatilizable compound may be introduced to thereaction zone separately from the feedstock injection point Suchintroduction may be upstream or downstream from the feedstock injectionpoint, provided the volatilizable compound is introduced upstream fromthe quench zone. For example, referring to FIG. 1, the volatilizablecompound may be introduced to zone Q at point 12 or any other point inthe zone. Upon volatilization and exposure to high temperatures in thereactor, the compound decomposes, and reacts with other species in thereaction zone, yielding silicon treated carbon black, such that thesilicon, or silicon containing species, becomes an intrinsic part of thecarbon black. An example of a silicon-containing species is silicaBesides volatalizable compounds, decomposible compounds which are notnecessarily volatilizable can also be used to yield the silicon-treatedcarbon black.

As discussed in further detail below, if the volatilizable compound isintroduced substantially simultaneously with the feedstock, thesilicon-treated regions are distributed throughout at least a portion ofthe carbon black aggregate.

In a second embodiment of the present invention, the volatilizablecompound is introduced to the reaction zone at a point after carbonblack formation has commenced but before the reaction stream has beensubjected to the quench. In this embodiment, silicon-treated carbonblack aggregates are obtained in which a silicon containing species ispresent primarily at or near the surface of the carbon black aggregate.

It has been found by the present inventors that the elastomericcompounds incorporating a treated carbon black may be additionallycompounded with one or more coupling agents to further enhance theproperties of the elastomeric compound. Coupling agents, as used herein,include, but are not limited to, compounds that are capable of couplingfillers such as carbon black or silica to an elastomer. Coupling agentsuseful for coupling silica or carbon black to an elastomer, are expectedto be useful with the silicon-treated carbon blacks. Useful couplingagents include, but are not limited to, silane coupling agents such asbis(3-triethoxysilylpropyl)tetrasulfane (Si-69),3-thiocyanatopropyl-triethoxy silane (Si-264, from Degussa AG, Germany),γ-mercaptopropyl-trimethoxy silane (A189, from Union Carbide Corp.,Danbury, Conn. ); zirconate coupling agents, such as zirconiumdineoalkanolatodi(3-mercapto) propionato-O (NZ 66A, from KenrichPetrochemicals, Inc., of Bayonne, N.J. ); titanate coupling agents;nitro coupling agents such asN,N′-bis(2-methyl-2-nitropropyl)-1,6-diaminohexane (Sumifine 1162, fromSumitomo Chemical Co., Japan); and mixtures of any of the foregoing. Thecoupling agents may be provided as a mixture with a suitable carrier,for example X50-S which is a mixture of Si-69 and N330 carbon black,available from Degussa AG.

The silicon-treated carbon black incorporated in the elastomericcompound of the present invention may be oxidized and/or combined with acoupling agent. Suitable oxidizing agents include, but are not limitedto, nitric acid and ozone. Coupling agents which may be used with theoxidized carbon blacks include, but are not limited to, any of thecoupling agents set forth above.

The silicon-treated carbon blacks of the present invention may have anorganic group attached.

One process for attaching an organic group to the carbon black involvesthe reaction of at least one diazonium salt with a carbon black in theabsence of an externally applied current sufficient to reduce thediazonium salt That is, the reaction between the diazonium salt and thecarbon black proceeds without an external source of electrons sufficientto reduce the diazonium salt. Mixtures of different diazonium salts maybe used in the process of the invention. This process can be carried outunder a variety of reaction conditions and in any type of reactionmedium, including both protic and aprotic solvent systems or slurries.

In another process, at least one diazonium salt reacts with a carbonblack in a protic reaction medium. Mixtures of different diazonium saltsmay be used in this process of the invention. This process can also becarried out under a variety of reaction conditions.

Preferably, in both processes, the diazonium salt is formed in situ. Ifdesired, in either process, the carbon black product can be isolated anddried by means known in the art. Furthermore, the resultant carbon blackproduct can be treated to remove impurities by known techniques. Thevarious preferred embodiments of these processes are discussed below.

These processes can be carried out under a wide variety of conditionsand in general are not limited by any particular condition. The reactionconditions must be such that the particular diazonium salt issufficiently stable to allow it to react with the carbon black. Thus,the processes can be carried out under reaction conditions where thediazonium salt is short lived. The reaction between the diazonium saltand the carbon black occurs, for example, over a wide range of pH andtemperature. The processes can be carried out at acidic, neutral, andbasic pH. Preferably, the pH ranges from about 1 to 9. The reactiontemperature may preferably range from 0° C. to 100° C.

Diazonium salts, as known in the art, may be formed for example by thereaction of primary amines with aqueous solutions of nitrous acid. Ageneral discussion of diazonium salts and methods for their preparationis found in Morrison and Boyd, Organic Chemistry, 5th Ed., pp. 973-983,(Allyn and Bacon, Inc. 1987) and March, Advanced Organic Chemistry:Reactions, Mechanisms, and Structures, 4th Ed., (Wiley, 1992). Accordingto this invention, a diazonium salt is an organic compound having one ormore diazonium groups.

The diazonium salt may be prepared prior to reaction with the carbonblack or, more preferably, generated in situ using techniques known inthe art. In situ generation also allows the use of unstable diazoniumsalts such as alkyl diazonium salts and avoids unnecessary handling ormanipulation of the diazonium salt. In particularly preferred processes,both the nitrous acid and the diazonium salt are generated in situ.

A diazonium salt, as is known in the art, may be generated by reacting aprimary amine, a nitrite and an acid. The nitrite may be any metalnitrite, preferably lithium nitrite, sodium nitrite, potassium nitrite,or zinc nitrite, or any organic nitrite such as for exampleisoamylnitrite or ethylnitrite. The acid may be any acid, inorganic ororganic, which is effective in the generation of the diazonium salt.Preferred acids include nitric acid, HNO₃, hydrochloric acid, HCl, andsulfuric acid, H₂SO₄.

The diazonium salt may also be generated by reacting the primary aminewith an aqueous solution of nitrogen dioxide. The aqueous solution ofnitrogen dioxide, NO₂/H₂O, provides the nitrous acid needed to generatethe diazonium salt.

Generating the diazonium salt in the presence of excess HCl may be lesspreferred than other alternatives because HCl is corrosive to stainlesssteel. Generation of the diazonium salt with NO₂/H₂O has the additionaladvantage of being less corrosive to stainless steel or other metalscommonly used for reaction vessels. Generation using H₂SO₄/NaNO₂ orHNO₃/NaNO₂ are also relatively non-corrosive.

In general, generating a diazonium salt from a primary amine, a nitrite,and an acid requires two equivalents of acid based on the amount ofamine used. In an in situ process, the diazonium salt can be generatedusing one equivalent of the acid. When the primary amine contains astrong acid group, adding a separate acid may not be necessary. The acidgroup or groups of the primary amine can supply one or both of theneeded equivalents of acid. When the primary amine contains a strongacid group, preferably either no additional acid or up to one equivalentof additional acid is added to a process of the invention to generatethe diazonium salt in situ. A slight excess of additional acid may beused. One example of such a primary amine is para-aminobenzenesulfonicacid (sulfanilic acid).

In general, diazonium salts are thermally unstable. They are typicallyprepared in solution at low temperatures, such as 0-5° C., and usedwithout isolation of the salt. Heating solutions of some diazonium saltsmay liberate nitrogen and form either the corresponding alcohols inacidic media or the organic free radicals in basic media.

However, the diazonium salt need only be sufficiently stable to allowreaction with the carbon black. Thus, the processes can be carried outwith some diazonium salts otherwise considered to be unstable andsubject to decomposition. Some decomposition processes may compete withthe reaction between the carbon black and the diazonium salt and mayreduce the total number of organic groups attached to the carbon black.Further, the reaction may be carried out at elevated temperatures wheremany diazonium salts may be susceptible to decomposition. Elevatedtemperatures may also advantageously increase the solubility of thediazonium salt in the reaction medium and improve its handling duringthe process. However, elevated temperatures may result in some loss ofthe diazonium salt due to other decomposition processes.

Reagents can be added to form the diazonium salt in situ, to asuspension of carbon black in the reaction medium, for example, water.Thus, a carbon black suspension to be used may already contain one ormore reagents to generate the diazonium salt and the processaccomplished by adding the remaining reagents.

Reactions to form a diazonium salt are compatible with a large varietyof functional groups commonly found on organic compounds. Thus, only theavailability of a diazonium salt for reaction with a carbon black limitsthe processes of the invention.

The processes can be carried out in any reaction medium which allows thereaction between the diazonium salt and the carbon black to proceed.Preferably, the reaction medium is a solvent-based system. The solventmay be a protic solvent, an aprotic solvent, or a mixture of solvents.Protic solvents are solvents, like water or methanol, containing ahydrogen attached to an oxygen or nitrogen and thus are sufficientlyacidic to form hydrogen bonds. Aprotic solvents are solvents which donot contain an acidic hydrogen as defined above. Aprotic solventsinclude, for example, solvents such as hexanes, tetrahydrofuran (THF),acetonitrile, and benzonitrile. For a discussion of protic and aproticsolvents see Morrison and Boyd, Organic Chemistry 5th Ed., pp. 228-231,(Allyn and Bacon, Inc. 1987).

The processes are preferably carried out in a protic reaction medium,that is, in a protic solvent alone or a mixture of solvents whichcontains at least one protic solvent. Preferred protic media include,but are not limited to water, aqueous media containing water and othersolvents, alcohols, and any media containing an alcohol, or mixtures ofsuch media The reaction between a diazonium salt and a carbon black cantake place with any type of carbon black, for example, in fluffy orpelleted form. In one embodiment designed to reduce production costs,the reaction occurs during a process for forming carbon black pellets.For example, a carbon black product of the invention can be prepared ina dry drum by spraying a solution or slurry of a diazonium salt onto acarbon black. Alternatively, the carbon black product can be prepared bypelletizing a carbon black in the presence of a solvent system, such aswater, containing the diazonium salt or the reagents to generate thediazonium salt in situ. Aqueous solvent systems are preferred.Accordingly, another embodiment provides a process for forming apelletized carbon black comprising the steps of: introducing a carbonblack and an aqueous slurry or solution of a diazonium salt into apelletizer, reacting the diazonium salt with the carbon black to attachan organic group to the carbon black, and pelletizing the resultingcarbon black having an attached organic group.

The pelletized carbon black product may then be dried using conventionaltechniques.

In general, the processes produce inorganic by-products, such as salts.In some end uses, such as those discussed below, these by-products maybe undesirable. Several possible ways to produce a carbon black productwithout unwanted inorganic by-products or salts are as follows:

First, the diazonium salt can be purified before use by removing theunwanted inorganic by-product using means known in the art. Second, thediazonium salt can be generated with the use of an organic nitrite asthe diazotization agent yielding the corresponding alcohol rather thanan inorganic salt Third, when the diazonium salt is generated from anamine having an acid group and aqueous NO₂, no inorganic salts areformed. Other ways may be known to those of skill in the art.

In addition to the inorganic by-products, a process may also produceorganic by-products They can be removed, for example, by extraction withorganic solvents. Other ways of obtaining products without unwantedorganic by-products may be known to those of skill in the art andinclude washing or removal of ions by reverse osmosis.

The reaction between a diazonium salt and a carbon black forms a carbonblack product having an organic group attached to the carbon black. Thediazonium salt may contain the organic group to be attached to thecarbon black. It may be possible to produce the carbon black products ofthis invention by other means known to those skilled in the art.

The organic group may be an aliphatic group, a cyclic organic group, oran organic compound having an aliphatic portion and a cyclic portion. Asdiscussed above, the diazonium salt employed in the processes can bederived from a primary amine having one of these groups and beingcapable of forming, even transiently, a diazonium salt. The organicgroup may be substituted or unsubstituted, branched or unbranched.Aliphatic groups include, for example, groups derived from alkanes,alkenes, alcohols, ethers, aldehydes, ketones, carboxylic acids, andcarbohydrates. Cyclic organic groups include, but are not limited to,alicyclic hydrocarbon groups (for example, cycloalkyls, cycloalkenyls),heterocyclic hydrocarbon groups (for example, pyrrolidinyl, pyrrolinyl,piperidinyl, morpholinyl, and the like), aryl groups (for example,phenyl, naphthyl, anthracenyl, and the like), and heteroaryl groups(imidazolyl, pyrazolyl, pyridinyl, thienyl, thiazolyl, furyl, indolyl,and the like). As the steric hinderance of a substituted organic groupincreases, the number of organic groups attached to the carbon blackfrom the reaction between the diazonium salt and the carbon black may bediminished.

When the organic group is substituted, it may contain any functionalgroup compatible with the formation of a diazonium salt. Preferredfunctional groups include, but are not limited to, R, OR, COR, COOR,OCOR, carboxylate salts such as COOLi, COONa, COOK, COO⁻NR₄ ⁺, halogen,CN, NR₂, SO₃H, sulfonate salts such as SO₃Li, SO₃Na, SO₃K, SO₃ ⁻NR₄ ⁺,OSO₃H, OSO₃ ⁻ salts, NR(COR), CONR₂, NO₂, PO₃H₂, phosphonate salts suchas PO₃HNa and PO₃Na₂, phosphate salts such as OPO₃HNa and OPO₃Na, N═NR,NR₃ ⁺X³¹, PR₃ ⁺X³¹; S_(k)R, SSO₃H, SSO₃ ⁻ salts, SO₂NRR′, SO₂SR, SNRR′,SNQ, SO₂NQ, CO₂NQ, S-(1,4-piperazinediyl)-SR, 2-(1,3-dithianyl)2-(1,3-dithiolanyl), SOR, and SO₂R. R and R′, which can be the same ordifferent, are independently hydrogen, branched or unbranched C₁-C₂₀substituted or unsubstituted, saturated or unsaturated hydrocarbon,e.g., alkyl, alkenyl, alkynyl, substituted or unsubstituted aryl,substituted or unsubstituted heteroaryl, substituted or unsubstitutedalkylaryl, or substituted or unsubstituted arylalkyl. The integer kranges from 1-8 and preferably from 2-4. The anion X³¹ is a halide or ananion derived from a mineral or organic acid. Q is (CH₂)_(w),(CH₂)_(x)O(CH₂)_(z), (CH₂)_(x)NR(CH₂)_(z), or (CH₂)_(x)S(CH₂)_(z), wherew is an integer from 2 to 6 and x and z are integers from 1 to 6.

A preferred organic group is an aromatic group of the formula A_(y)Ar—,which corresponds to a primary amine of the formula A_(y)ArNH₂. In thisformula, the variables have the following meanings: Ar is an aromaticradical such as an aryl or heteroaryl group. Preferably, Ar is selectedfrom the group consisting of phenyl, naphthyl, anthracenyl,phenanthrenyl, biphenyl, pyridinyl, benzothiadiazolyl, andbenzothiazolyl; A is a substituent on the aromatic radical independentlyselected from a preferred functional group described above or A is alinear, branched or cyclic hydrocarbon radical (preferably containing 1to 20 carbon atoms), unsubstituted or substituted with one or more ofthose functional groups; and y is an integer from 1 to the total numberof —CH radicals in the aromatic radical. For instance, y is an integerfrom 1 to 5 when Ar is phenyl, 1 to 7 when Ar is naphthyl, 1 to 9 whenAr is anthracenyl, phenanthrenyl, or biphenyl, or 1 to 4 when Ar ispyridinyl. In the above formula, specific examples of R and R′ areNH₂—C₆H₄—, CH₂CH₂—C₆H₄—NH₂, CH₂—C₆H₄—NH₂, and C₆H₅.

Another preferred set of organic groups which may be attached to thecarbon black are organic groups substituted with an ionic or anionizable group as a functional group. An ionizable group is one whichis capable of forming an ionic group in the medium of use. The ionicgroup may be an anionic group or a cationic group and the ionizablegroup may form an anion or a cation.

Ionizable functional groups forming anions include, for example, acidicgroups or salts of acidic groups. The organic groups, therefore, includegroups derived from organic acids. Preferably, when it contains anionizable group forming an anion, such an organic group has a) anaromatic group and b) at least one acidic group having a pKa of lessthan 11, or at least one salt of an acidic group having a pKa of lessthan 11, or a mixture of at least one acidic group having a pKa of lessthan 11 and at least one salt of an acidic group having a pKa of lessthan 11. The pKa of the acidic group refers to the pKa of the organicgroup as a whole, not just the acidic substituent. More preferably, thepKa is less than 10 and most preferably less than 9. Preferably, thearomatic group of the organic group is directly attached to the carbonblack. The aromatic group may be further substituted or unsubstituted,for example, with alkyl groups. More preferably, the organic group is aphenyl or a naphthyl group and the acidic group is a sulfonic acidgroup, a sulfinic acid group, a phosphonic acid group, or a carboxylicacid group. Examples of these acidic groups and their salts arediscussed above. Most preferably, the organic group is a substituted orunsubstituted sulfophenyl group or a salt thereof; a substituted orunsubstituted (polysulfo)phenyl group or a salt thereof; a substitutedor unsubstituted sulfonaphthyl group or a salt thereof; or a substitutedor unsubstituted (polysulfo)naphthyl group or a salt thereof. Apreferred substituted sulfophenyl group is hydroxysulfophenyl group or asalt thereof.

Specific organic groups having an ionizable functional group forming ananion (and their corresponding primary amines) are p-sulfophenyl(p-sulfanilic acid), 4-hydroxy-3-sulfophenyl(2-hydroxy-5-amino-benzenesulfonic acid), and 2-sulfoethyl(2-aminoethanesulfonic acid). Other organic groups having ionizablefunctional groups forming anions can also be used.

Amines represent examples of ionizable functional groups that formcationic groups. For example, amines may be protonated to form ammoniumgroups in acidic media. Preferably, an organic group having an aminesubstituent has a pKb of less than 5. Quaternary ammonium groups (—NR₃⁺) and quaternary phosphonium groups (—PR₃ ⁺) also represent examples ofcationic groups. Preferably, the organic group contains an aromaticgroup such as a phenyl or a naphthyl group and a quaternary ammonium ora quaternary phosphonium group. The aromatic group is preferablydirectly attached to the carbon black. Quaternized cyclic amines, andeven quatemized aromatic amines, can also be used as the organic group.Thus, N-substituted pyridinium compounds, such as N-methyl-pyridyl, canbe used in this regard. Examples of organic groups include, but are notlimited to, (C₅H₄N)C₂H₅ ⁺, C₆H₄(NC₅H₅)⁺, C₆H₄COCH₂N(CH₃)₃ ⁺,C₆H₄COCH₂(NC₅H₅)⁺, (C₅H₄N)CH₃ ⁺, and C₆H₄CH₂N(CH₃)₃ ⁺.

An advantage of the carbon black products having an attached organicgroup substituted with an ionic or an ionizable group is that the carbonblack product may have increased water dispersibility relative to thecorresponding untreated carbon black. Water dispersibility of a carbonblack product increases with the number of organic groups attached tothe carbon black having an ionizable group or the number of ionizablegroups attached to a given organic group. Thus, increasing the number ofionizable groups associated with the carbon black product shouldincrease its water dispersibility and permits control of the waterdispersibility to a desired level. It can be noted that the waterdispersibility of a carbon black product containing an amine as theorganic group attached to the carbon black may be increased byacidifying the aqueous medium.

Because the water dispersibility of the carbon black products depends tosome extent on charge stabilization, it is preferable that the ionicstrength of the aqueous medium be less than 0.1 molar. More preferably,the ionic strength is less than 0.01 molar.

When such a water dispersible carbon black product is prepared, it ispreferred that the ionic or ionizable groups be ionized in the reactionmedium. The resulting product solution or slurry may be used as is ordiluted prior to use. Alternatively, the carbon black product may bedried by techniques used for conventional carbon blacks. Thesetechniques include, but are not limited to, drying in ovens and rotarykilns. Overdrying, however, may cause a loss in the degree of waterdispersibility.

In addition to their water dispersibility, carbon black products havingan organic group substituted with an ionic or an ionizable group mayalso be dispersible in polar organic solvents such as dimethylsulfoxide(DMSO), and formamide. In alcohols such as methanol or ethanol, use ofcomplexing agents such as crown ethers increases the dispersibility ofcarbon black products having an organic group containing a metal salt ofan acidic group.

Aromatic sulfides encompass another group of preferred organic groups.Carbon black products having aromatic sulfide groups are particularlyuseful in rubber compositions. These aromatic sulfides can berepresented by the formulas Ar(CH₂)_(q)S_(k)(CH₂)_(r)Ar′ orA—(CH₂)_(q)S_(k)(CH₂)_(r)Ar″ wherein Ar and Ar′ are independentlysubstituted or unsubstituted arylene or heteroarylene groups, Ar″ is anaryl or heteroaryl group, k is 1 to 8 and q and r are 0-4. Substitutedaryl groups would include substituted alkylaryl groups. Preferredarylene groups include phenylene groups, particularly p-phenylenegroups, or benzothiazolylene groups. Preferred aryl groups includephenyl, naphthyl and benzothiazolyl. The number of sulfurs present,defined by k preferably ranges from 2 to 4. Preferred carbon blackproducts are those having an attached aromatic sulfide organic group ofthe formula —(C₆H₄)—S_(k)—(C₆H₄)—, where k is an integer from 1 to 8,and more preferably where k ranges from 2 to 4. Particularly preferredaromatic sulfide groups are bis-para-(C₆H₄)—S₂—(C₆H₄)— andpara-(C₆H₄)—S₂—(C₆H₅) The diazonium salts of these aromatic sulfidegroups may be conveniently prepared from their corresponding primaryamines, H₂N—Ar—S_(k)—Ar′—NH₂ or H₂N—Ar—S_(k)—Ar″. Preferred groupsinclude dithiodi-4,1-phenylene, tetrathiodi-4,1-pbenylene,phenyldithiophenylene, dithiodi-4,1-(3-chlorophenylene),-(4-C₆H₄)—S—S-(2-C₇H₄NS), -(4-C₆H₄)—S—S-(4-C₆H₄)—OH, -6-(2-C₇H₃NS)—SH,-(4-C₆H₄) —CH₂CH₂—S—S—CH₂CH₂-(4-C₆H₄)—,-(4-C₆H₄)—CH₂CH₂—S—S—S—CH₂CH₂-(4-C₆H₄)—, -(2-C₆H₄)—S—S- (2-C₆H₄)—,-(3-C₆H₄)—S—S-(3-C₆H₄)—, -6- (C₆H₃N₂S), -6-(2-C₇H₃NS)—S—NRR′ where RR′is —CH₂CH₂OCH₂CH₂—, -(4-C₆H₄)—S—S—S—S-(4- C₆H₄)—, -(4-C₆H₄)—CH═CH₂,-(4-C₆H₄)—S—SO₃H, -(4-C₆H₄)—SO₂NH-(4-C₆H₄)—S—S-(4-C₆H₄)—NHSO₂-(4-C₆H₄)—,-6-(2-C₇H₃NS)—S—S-2-(6-C₇H₃NS)—, -(4-C₆H₄)—S—CH₂-(4-C₆H₄)—,-(4-C₆H₄)—SO₂—S-(4-C₆H₄)—, -(4-C₆H₄)—CH₂—S—CH₂-(4-C₆H₄)—,-(3-C₆H₄)—CH₂—S—CH₂-(3-C₆H₄)—, -(4-C₆H₄)—CH₂—S—S—CH₂-(4-C₆H₄)—,-(3-C₆H₄)—CH₂—S—S—CH₂-(3-C₆H₄)—, -(4-C₆H₄)—S—NRR′ where RR′ is—CH₂CH₂OCH₂CH₂—, -(4-C₆H₄)—SO₂NH—CH₂CH₂—S—S—CH₂CH₂—NHSO₂-(4-C₆H₄)—,-(4-C₆H₄)-2-(1,3-dithianyl;), and-(4-C₆H₄)—S-(1,4-piperizinediyl)-S-(4-C₆H₄)—.

Another preferred set of organic groups which may be attached to thecarbon black are organic groups having an aminophenyl, such as(C₆H₄)—NH₂, (C₆H₄)—CH₂—(C₆H₄)—NH_(2,) (C₆H₄)—SO₂—(C₆H₄)—NH₂. Preferredorganic groups also include aromatic sulfides, represented by theformulas Ar—S_(n)—Ar′ or Ar—S_(n)—Ar″, wherein Ar and Ar′ areindependently arylene groups, Ar″ is an aryl and n is 1 to 8. Methodsfor attaching such organic groups to carbon black are discussed in U.S.patent applications Ser. Nos. 08/356,660, 08/572,525, and 08/356,459,the disclosures of which are fully incorporated by reference herein.

As stated earlier, the silicon-treated carbon black may also be modifiedto have at least one organic group attached to the silicon-treatedcarbon black. Alternatively, a mixture of silicon-treated carbon blackand a modified carbon black having at least one attached organic groupmay be used.

Furthermore, it is within the bounds of this application to also use amixture of silica and silicon-treated carbon black. Also, anycombination of additional components with the silicon-treated carbonblack may be used such as one or more of the following:

a) silicon-treated carbon black with an attached organic groupoptionally treated with silane coupling agents;

b) modified carbon black having an attached organic group;

c) silica;

d) modified silica, for example, having an attached organic group,and/or

e) carbon black. Examples of silica include, but are not limited to,silica, precipitated silica, amorphous silica, vitreous silica, fumedsilica, fused silica, silicates (e.g., alumino silicates) and other Sicontaining fillers such as clay, talc, wollastonite, etc. Silicas arecommercially available from such sources as Cabot Corporation under theCab-O-Sil® tradename; PPG Industries under the Hi-Sil and Ceptanetradenames; Rhone-Poulenc under the Zeosil tradename; and Degussa AGunder the Ultrasil and Coupsil tradenames.

The elastomeric compounds of the present invention may be prepared fromthe treated carbon blacks by compounding with any elastomer includingthose useful for compounding a carbon black.

Any suitable elastomer may be compounded with the treated carbon blacksto provide the elastomeric compounds of the present invention. Suchelastomers include, but are not limited to, rubbers, homo- orco-polymers of 1,3-butadiene, styrene, isoprene, isobutylene,2,3-dimethyl-1,3-butadiene, acrylonitrile, ethylene, and propylenePreferably, the elastomer has a glass transition temperature (Tg) asmeasured by differential scanning colorimetry (DSC) ranging from about−120° C. to about 0° C. Examples include, but are not limited,styrene-butadiene rubber (SBR), natural rubber, polybutadiene,polyisoprene, and their oil-extended derivatives. Blends of any of theforegoing may also be used.

Among the rubbers suitable for use with the present invention arenatural rubber and its derivatives such as chlorinated rubber. Thesilicon-treated carbon black products of the invention may also be usedwith synthetic rubbers such as: copolymers of from about 10 to about 70percent by weight of styrene and from about 90 to about 30 percent byweight of butadiene such as copolymer of 19 parts styrene and 81 partsbutadiene, a copolymer of 30 parts styrene and 70 parts butadiene, acopolymer of 43 parts styrene and 57 parts butadiene and a copolymer of50 parts styrene and 50 parts butadiene; polymers and copolymers ofconjugated dienes such as polybutadiene, polyisoprene, polychloroprene,and the like, and copolymers of such conjugated dienes with an ethylenicgroup-containing monomer copolymerizable therewith such as styrene,methyl styrene, chlorostyrene, acrylonitrile,2-vinyl-pyridine,5-methyl2-vinylpyridine,5-ethyl-2-vinylpyridine, 2-methyl-5-vinylpyridine,alkyl-substituted acrylates, vinyl ketone, methyl isopropenyl ketone,methyl vinyl either, alphamethylene carboxylic acids and the esters andamides thereof such as acrylic acid and dialkylacrylic acid amide; alsosuitable for use herein are copolymers of ethylene and other high alphaolefins such as propylene, butene-1 and pentene-1.

The rubber compositions of the present invention can therefore containan elastomer, curing agents, reinforcing filler, a coupling agent, and,optionally, various processing aids, oil extenders, and antidegradents.In addition to the examples mentioned above, the elastomer can be, butis not limited to, polymers (e.g., homopolymers, copolymers, andterpolymers) manufactured from 1,3 butadiene, styrene, isoprene,isobutylene, 2,3-dimethyl-1,3 butadiene, acrylonitrile, ethylene,propylene, and the like. It is preferred that these elastomers have aglass transition point (Tg), as measured by DSC, between −120° C. and 0°C. Examples of such elastomers include poly(butadiene),poly(styrene-co-butadiene), and poly(isoprene).

Elastomeric compositions also include vulcanized compositions (VR),thermoplastic vulcanizates (TPV), thermoplastic elastomers (TPE) andthermoplastic polyolefins (TPO). TPV, TPE, and TPO materials are furtherclassified by their ability to be extruded and molded several timeswithout loss of performance characteristics.

In making the elastomeric compositions, one or more curing agents suchas, for example, sulfur, sulfur donors, activators, accelerators,peroxides, and other systems used to effect vulcanization of theelastomer composition may be used.

Formulation of the silicon-treated carbon blacks of the presentinvention with elastomers are contemplated to have advantages notrealized when such elastomers are formulated with conventional carbonblacks. Set forth below in Table 1A is a list of certain of theelastomers which are particularly useful for industrial rubberapplications; and preferred loading ratios with the silicon-treatedcarbon blacks of the present invention, designated as parts of carbonblack per hundred parts of elastomer (PHR); contemplated benefitsobtained by such composition compared to the same composition employinga conventional carbon black; and useful industrial applications for eachcomposition corresponding, where applicable, to the contemplated benefitobtained with such composition.

TABLE 1A FIELD OF POLYMER LOADING BENEFITS UPON FORMING APPLICATIONEthylene Propylele 50-250 PHR INCREASED UHF HEATING RATES WEATHERSTRIPDiene Monomer 100-200 PHR INCREASED TEAR STRENGTH WEATHERSTRIP (EPDM)REDUCED IRIDESCENCE WEATHERSTRIP IMPROVED HEAT AGING RESISTANCE HOSEHIGHER ELECTRICAL RESISTIVITY HOSE INCREASED ELONGATION @ GIVEN HARDNESSHOSE LONGER FATIGUE LIFE ENGINE MOUNTS LOWER STRING RATIO FOR A GIVENTAN δ ENGINE MOUNTS IMPROVED RESILENCE ENGINE MOUNTS Poly-Chloroprene10-150 phr LOWER SPRING RATIO FOR A GIVEN (NEOPRENE) 20-80 phr TAN δENGINE MOUNTS IMPROVED GLYCOL RESISTANCE SEALS IMPROVED RESILENCE SEALS,HOSE LOWER HEAT BUILD-UP BELTS Natural Rubber 10-150 phr LOWER SPRINGRATIO FOR A GIVEN (NR) 20-80 phr TAN δ ENGINE MOUNTS HIGHER CUT/CHIPRESISTANCE BELTS Hydrogenated 10-150 phr LOWER SPRING RATIO FOR A GIVENNitrile Butadiene 20-80 phr TAN δ ENGINE MOUNTS Rubber INCREASED HIGHTEMP TEAR (HNBR) RESISTANCE MOUNTS, SEALS IMPROVED RESILIENCE SEALS,HOSE LOWER HEAT BUILD-UP BELTS Styrene Butadiene 10-150 pHr HIGHERCUT/CHIP RESISTANCE BELTS Rubber (SBR) Ethylene Vinyl 10-150 phrIMPROVED PHYSICAL PROPERTIES HOSE Acetate (EVA)

It has been found that in certain tire usages, cut-chip resistance is anecessary property, especially with regard to trucks, for instance,travelling between pavements and dirt surfaces. In particular, aftertravelling on a pavement, the tires build up heat, which, upon enteringa job site, can result in excess cutting and chipping of the tire on arough terrain. It has been discovered that when the silicon-treatedcarbon black of the present invention is incorporated into a tire treadcompound (or other parts of the tire including sidewalls), the heatbuild-up of the tire tread characterized by tan δ (delta) at 70°, can bereduced, tear strength can be increased, and elongation properties canbe increased, while maintaining acceptable tensile strength of the treadcompound. With an improvement in these properties, the cut-chipresistance of the tread can improve substantially, resulting in a longerlasting, better performing tire tread.

In order to improve the above-described properties, thereby obtainingimproved cut-chip resistance, the silicon-treated carbon black of thepresent invention may be used in a blend with other fillers such assilica and carbon black, as well as with a coupling agent.

The silicon-treated carbon blacks of the present invention can also beused in a wire breaker compound in tires. With the use of wire breakercompounds containing the silicon-treated carbon blacks, excellentadhesion can be obtained to the steel cord. Additionally, it is alsopossible to reduce heat buildup in this component of the tire.

The contemplated benefits obtained with the compositions set forth inTable 1A are characterized by expected properties compared to the samecomposition made with conventional (non-silicon-treated) carbon black.Evaluation of these properties for a given silicon-treated carbonblack/elastomer composition is done by conducting comparative tests.Most of the properties set forth in Table IA are determined by routinetests known to those skilled in the art. Other tests are brieflydescribed below:

Hardness refers to Shore A Hardness, which is determined according tothe procedure set forth in ASTM D-2240-86.

Resilience may be determined according to the procedure set forth inASTM D1054, utilizing a ZWICK Rebound Resilience Tester, Model 5109,manufactured by Zwick of America, Inc., Post Office Box 997, EastWindsor, Conn. 06088.

The UHF microwave receptivity may be measured by a Dielecmetre (suppliedby Total Elastomers in France). The UHF microwave receptivity ischaracterized by a coefficient, α, which is defined as

α=(150° C.−80° C.)/(t ₁₅₀ −t ₈₀)[°C./s]

where t₁₅₀ and t₈₀ are the times needed for samples to reach 150° C. and80° C. respectively. α is the heating rate between temperatures 80° and150° C.

The electrical resistivity of the composition may be measured bypainting samples 2 inches wide by 6 inches long by 0.085 inch thick witha half inch width of silver paint. The sample is then conditione d toproduce a stable reading by cycling from room temperature to 100° C. andback to room temperature, followed by aging at 90° C. for 24 hours. Thestabilized resistivity was measured at the end of the aging cycle, andonce again after the sample was allowed to cool back to roomtemperature.

The resultant elastomeric compounds containing treated carbon black andoptionally containing one or more coupling agents may be used forvarious elastomeric products such as treads for vehicle tires,industrial rubber products, seals, timing belts, power transmissionbelting, and other rubber goods. When utilized in tires, the elastomericcompounds may be used in the tread or in other components of the tire,for example, the carcass and sidewall.

Tread compounds produced with the present elastomeric compoundsincorporating a silicon-treated carbon black but without a couplingagent, provide improved dynamic hysteresis characteristics. However,elastomeric compounds incorporating a silicon-treated carbon black and acoupling agent demonstrate further improved characteristics when testedfor dynamic hysteresis at different temperatures and resistance toabrasion. Therefore, a tire incorporating a tread compound manufacturedwith an elastomeric compound of the present invention, incorporatingboth a silicon-treated carbon black and a coupling agent willdemonstrate even lower rolling resistance, good traction and better wearresistance when compared with a tire made with a tread compoundincorporating the treated carbon black but lacking the coupling agent.

The following examples illustrate the invention without limitation.

EXAMPLE Example 1

Silicon-treated carbon blacks according to the present invention wereprepared using a pilot scale reactor generally as described above, andas depicted in FIG. 1 and having the dimensions set forth below: D₁=4inches, D₂=2 inches, D₃=5 inches, L₁=4 inches, L₂=5 inches, L₃=7 inches,L₄=1 foot and Q=4.5 feet. The reaction conditions set forth in Table 1below, were employed.

These conditions result in the formation of a carbon black identified bythe ASTM designation N234. A commercially available example of N234 isVulcan® 7H from Cabot Corporation, Boston, Mass. These conditions werealtered by adding a volatilizable silicon-containing compound into thereactor, to obtain a silicon-treated carbon black. The flow rate of thevolatilizable compound was adjusted to alter the weight percent ofsilicon in the treated carbon black. The weight percent of silicon inthe treated carbon black was determined by the ashing test, conductedaccording to ASTM procedure D-1506.

One such new treated carbon black was made by injecting anorgano-silicon compound, namely octamethyl-cyclotetrasiloxane (OMTS),into the hydrocarbon feedstock. This compound is sold as “D4” by DowCorning Corporation, Midland, Mich. The resultant silicon-treated carbonblack is identified herein as OMTS-CB. A different silicon-treatedcarbon black (TEOS-CB) was prepared by introducing a secondsilicon-containing volatilizable compound, tetraethoxy silane, (sold asTEOS, by Huls America, Piscataway, N.J.), into the hydrocarbonfeedstock.

Since changes in reactor temperature are known to alter the surface areaof the carbon black, and reactor temperature is very sensitive to thetotal flow rate of the feedstock in the injection zone (zone 3 in FIG.1), the feedstock flow rate was adjusted downward to approximatelycompensate for the introduction of the volatilizable silicon-containingcompound, such that a constant reactor temperature was maintained. Thisresults in an approximately constant external surface area (as measuredby t area) for the resultant carbon blacks. All other conditions weremaintained as necessary for manufacturing N234 carbon black. A structurecontrol additive (potassium acetate solution) was injected into thefeedstock to maintain the specification structure of the N234 carbonblack. The flow rate of this additive was maintained constant in makingthe silicon-treated carbon blacks described throughout the followingexamples.

The external surface area (t-area) was measured following the samplepreparation and measurement procedure described in ASTM D3037—Method Afor Nitrogen surface area For this measurement, the nitrogen adsorptionisotherm was extended up to 0.55 relative pressure. The relativepressure is the pressure (P) divided by the saturation pressure (P₀)(the pressure at which the nitrogen condenses). The adsorption layerthickness (t₁) was then calculated using the relation:$t_{1} = \frac{13.99}{\sqrt{\left. {0.034 - {\log \quad \left( {P/P_{0}} \right)}} \right\rbrack}}$

The volume (V) of nitrogen adsorbed was then plotted against t₁. Astraight line was then fitted through the data points for t, valuesbetween 3.9 and 6.2 Angstroms. The t-area was then obtained from theslope of this line as follows:

TABLE 1 Carbon Black Conditions N234 TEOS-CB OMTS-CB Air Rate, kscfh12.8 12.8 12.8 Gas Rate, kscfh 0.94 0.94 0.94 feedstock rate, lbs/hr 166139 155 Si compound rate, lbs/hr 0 16 5

The resultant carbon blacks were analyzed for surface area and siliconcontent. These values are set forth in Table 2 below:

TABLE 2 Carbon Black Properties N234 TEOS-CB OMTS-CB % Silicon in CarbonBlack 0.02 2.85 2.08 DBP, cc/100 g 125.0 114.0 115.0 CDBP, cc/100 g101.5 104.1 103.5 t-Area, m²/g 117.0 121.0 121.0 N₂ area, m²/g 120.4136.0 133.0

Example 2

A scanning transmission electron microscope (STEM) coupled to an energydispersive X-ray analyzer, was used to further characterize thesilicon-treated carbon black. The following Table 3 compares N234,OMTS-CB (prepared according to Example 1) and N234 to which 3.7% byweight silica (L90, sold as CAB-O-SIL® L90, by Cabot Corporation,Boston, Mass.) was added to form a mixture. As described below, the STEMsystem may be used to examine an individual aggregate of carbon blackfor elemental composition. A physical mixture of carbon black and silicawill result in the identification of silica aggregates which show mostlysilicon signal and little or background carbon signal. Thus, whenmultiple aggregates are examined in a mixture, some of the aggregateswill show a high Si/C signal ratio, corresponding to aggregates ofsilica.

Five mg of carbon black was dispersed into 20 ml of chloroform andsubjected to ultrasonic energy using a probe sonicator (W-385 HeatSystems Ultra Sonicator). A 2 ml aliquot was then dispersed into 15 mlof chloroform using a probe sonicator for three minutes. The resultingdispersion was placed on a 200 mesh nickel grid with aluminum substrate.The grid was then placed under a Fisons HB501 Scanning TransmissionElectron Microscope (Fisons, West Sussex, England) equipped with anOxford Link AN10000 Energy Dispersive X-ray Analyzer (Oxford Link,Concord, Mass.).

Initially the grid was scanned for potential silica aggregates at lowmagnification (less than 200,000X). This was done by searching foraggregates that had a Si/C count ratio greater than unity. After thisinitial scan, typically thirty aggregates were selected for detailedanalysis at higher magnification (from between 200,000X and 2,000,000X).The selected aggregates included all of the aggregates which containedSi/C count ratios greater than unity, as identified by the initial scan.The highest ratios of Si/C counts thus determined are set forth in Table3 for N234, OMTS-CB and a mixture of N234 and silica.

TABLE 3 Ratio of Si/C Signal Measured with STEM % Si in Highest Ratio ofModified Sample Si/C Counts per Aggregate N234 0 0.02 OMTS-CB 3.28 0.27N234 + 3.7% silica 1.7 49 (L90)

Thus, a well dispersed mixture of carbon black and silica having thesame silicon content as the OMTS-CB shows 180 times higher peak Si/Ccounts. This data shows that the OMTS-CB carbon black is not a simplephysical mixture of silica and carbon black, but rather that the siliconis a part of the intrinsic chemical nature of the carbon black.

Example 3

HF Treatment

Hydrofluoric acid (HF) is able to dissolve silicon compounds but doesnot react with carbon. Thus, if either a conventional (untreated) carbonblack or a mixture of silica and carbon black is treated with HF, thesurface and surface area of the carbon black will remain unchanged,because it is unaffected by the dissolution of the silicon compoundsremoved from the mixture. However, if silicon containing species aredistributed throughout at least a portion, including the surface, of thecarbon black aggregate, the surface area will markedly increase asmicropores are formed as the silicon compound is dissolved out of thecarbon black structure.

Five grams of the carbon black to be tested were extracted with 100 mlof 10% v/v hydrofluoric acid for 1 hour. The silicon content andnitrogen surface area were measured before and after the HF treatmentThe results are shown in Table 4.

TABLE 4 HF Treatment % Si % Si N₂SA N₂SA Before HF After HF Before HFAfter HF Treatment Treatment Treatrnent Treatment N234 0.02 0.05 123 123OMTS-CB 3.3 0.3 138 180

Photomicrographs were taken of the carbon black samples before and afterHF treatment. The photomicrographs are shown in FIGS. 4a- 4 d. Thesephotographs show that the silicon-treated carbon blacks have a roughersurface, consistent with increased microporosity after the HF treatment,compared to the untreated carbon black.

Example 3A

Another silicon-treated carbon black was made by injecting TEOS into thereaction zone of the reactor immediately (one foot) downstream from thehydrocarbon feedstock injection plane, as indicated at injection point12 in FIG. 1. All other reaction conditions were maintained as requiredfor manufacturing N234 black, as described in Example 1. The TEOS flowrate was adjusted to 17.6 lbs per hour.

The resultant black was analyzed for silicon content and surface area,before and after HF extraction as described in Example 3. The resultsare described in Table 4A.

TABLE 4A TEOS-CB′ - manufactured by injection of TEOS into reaction zone% Si N₂ Area Before HF 2.27 127.7 After HF 0.04 125.8

Thus, no increase in N₂ surface area was seen after HF extraction of theTEOS-CB′. Analysis of the aggregates by the STEM procedure described inExample 2 also showed silicon to be present in the aggregates and not asindependent silica entities. These results show that in this case thesilicon-containing species of the silicon-treated carbon blacks areprimarily located near the surface.

Example 4

Preparation of Elastomeric Compositions

The carbon blacks of the previous Examples were used to make elastomericcompounds Elastomeric compositions incorporating the silicon-treatedcarbon blacks discussed above, were prepared using the followingelastomers: solution SBR (Duradene 715 and Cariflex S-1215, fromFirestone Synthetic Rubber & Latex Co., Akron, Ohio), functionalizedsolution SBR (NS 114 and NS 116 from Nippon Zeon Co., SL 574 and TO589from Japan Synthetic Rubber Co.), emulsion SBR (SBR 1500, from CopolymerRubber & Chemicals, Corp., Baton Rouge, La.), and natural rubber (SMR5,from Malaysia).

The elastomeric compositions were prepared according to the followingformulation:

TABLE 5 Ingredient Parts by weight elastomer 100 carbon black 50 zincoxide 3 stearic acid 2 Flexzone 7P ® 1 Durax ® 1.25 Captax ® 0.2 sulfur1.75 Si-69 (optional) 3 or 4

Flexzone 7P®, N-(1,3-dimethyl butyl)-N′-phenyl-p-phenylene diamine, isan anti-oxidant available from Uniroyal Chemical Co., Middlebury, Conn.Durax®, N-cyclohexane-2-benzothiazole sulphenamide, is an acceleratoravailable from R.T. Vanderbilt Co., of Norwalk, Conn., and Captax®,2-mercaptobenzothiazole, is an accelerator available from R.T.Vanderbilt Co.

The elastomeric compounds were prepared using a two-stage mixingprocedure. The internal mixer used for preparing the compounds was aPlasti-Corder EPL-V (obtained from C.W. Brabender, South Hackensack,N.J.) equipped with a cam-type mixing head (capacity 600 ml). In thefirst stage, the mixer was set at 80° C., and the rotor speed was set at60 rpm. After the mixer was conditioned to 100° C. by heating thechamber with a dummy mixture, the elastomer was loaded and masticatedfor 1 minute. Carbon black, pre-blended with zinc oxide (obtained fromNew Jersey Zinc Co., New Jersey), and optionally a coupling agent, wasthen added. After three minutes, stearic acid (obtained from EmeryChemicals, Cincinnati, Ohio) and anti-oxidant were added. Mixing wascontinued for an additional two minutes. The stage 1 masterbatch wasthen dumped from the mixer at five minutes total. This was then passedthrough an open mill (four inch, two-roll mill, obtained from C.W.Brabender, South Hackensack, N.J.) three times and stored at roomtemperature for two hours.

In the second stage, the mixing chamber temperature was set to 80° C.and the rotor speed was set to 35 rpm. After the mixer was conditionedthe masterbatch from stage one was loaded and mixed for one minute. Thecurative package (including sulfur, Durax and Captax) was then added Thematerial was dumped from the mixer at two minutes and passed through theopen mill three times.

Batches of the compounds were prepared as described for the carbonblacks in the previous Examples. The same grade of conventional carbonblack was used as a control. For each carbon black, two batches wereprepared. The first batch was made using Si-69 as the coupling agent.The second batch was made without a coupling agent. After mixing, eachof the elastomeric compositions was cured at 145° C. to an optimum curestate according to measurements made with a Monsanto ODR Rheometer.

Elastomeric compounds employing the elastomers set forth in Table 1A maybe formulated by following the foregoing procedure.

Example 5

Bound Rubber Test

The bound rubber content of an elastomeric compound incorporating carbonblack can be taken as a measure of the surface activity of the carbonblack The higher the bound rubber content, the higher the surfaceactivity of the carbon black.

Bound rubber was determined by extraction of an elastomeric compoundwith toluene at room temperature. The bound rubber is the elastomerremaining after extraction by the solvent. The elastomer used wassolution SBR (SSBR) Duradene 715 without a coupling agent, as describedabove in Example 4.

As seen in FIG. 2, the bound rubber was determined for a series ofblends of silica and carbon black, which serve as a reference againstwhich to compare the bound rubber of the silicon-treated carbon black.The results of the bound rubber measurements for the two sets ofcompounds are plotted against their equivalent silica content in FIG. 2.For the treated carbon blacks, the equivalent silica content is atheoretical value calculated from the total silicon as measured byashing. It is seen that silicon-treated carbon blacks yield a higherbound rubber than their conventional counterparts. This suggests thatthe treated carbon black surface is relatively more active. Moreover, asshown in FIG. 2, the bound rubber content of treated carbon black-filledcompounds lie well above the reference line generated from the blends ofcarbon black and silica This confirms that the treated carbon black isnot a physical mixture of silica and carbon black.

Example 6

Dynamic Hysteresis and Abrasion Resistance

The dynamic hysteresis and abrasion resistance rates were measured forthe elastomeric compositions produced according to Example 4 above.

Abrasion resistance was determined using an abrader, which is based on aLamboum-type machine as described in U.S. Pat. No. 4,995,197, herebyincorporated by reference. The tests were carried out at 14% slip. Thepercentage slip is determined based on the relative velocities of asample wheel and a grindstone wheel. The abrasion resistance index iscalculated from the mass loss of the elastomeric compound. Dynamicproperties were determined using a Rheometrics Dynamic Spectrometer II(RDS II, Rheometrics, Inc., N.J.) with strain sweep. The measurementswere made at 0 and 70° C. with strain sweeps over a range of doublestrain amplitude (DSA) from 0.2 to 120%. The maximum tan δ values on thestrain sweep curves were taken for comparing the hysteresis amongelastomeric compounds as can be seen in FIGS. 3a and 3 b. Alternatively,hysteresis measurements were made by means of temperature sweeps at aDSA of 5% and a frequency of 10 Hz. The temperature range was from −60°C. to 100° C., as seen in FIG. 3c.

TABLE 6 Dynamic Hysteresis Data tan δ tan δ abrasion at SSBRComposition^(a) Si-69 at 0° C. at 70° C. 14% slip N234 0 0.400 0.189 100N234 3 0.429 0.170 103.5 OMTS-CB 0 0.391 0.175 84.4 OMTS-CB 3 0.4350.152 110.5 TEOS-CB 0 0.400 0.167 78.1 TEOS-CB 3 0.433 0.142 97.2 ^(a)Duradene 715; two stage mixing.

As seen in Table 6 above, tan δ at 70° C. values were reduced by 7%, tanδ at 0° C. values reduced by 2.3% and the wear resistance was reduced by15%, for the SSBR samples when OMTS-CB was substituted for N234.However, when the Si-69 coupling agent was incorporated into thecomposition, the wear resistance for the OMTS-CB sample improved to 110%of the value for N234. The tan δ at 70° C. values decreased by 19.6%compared to N234 without coupling agent and 10.5% compared to N234 withcoupling agent. The tan δ at 0° C. values increased by 11% when thecoupling agent was added to the OMTS-CB, compared to OMTS-CB withoutcoupling agent. Similarly, for TEOS-CB, the tan δ at 70° C. value isreduced by 11.6%, the tan δ at 0° C. value is unchanged and the wear isreduced by 21.9%. When compounded with the coupling agent, the tan δ at70° C. value is reduced by 24.9%, the tan δ at 0° C. value is increasedby 8.3% and the wear decreased by only 2.8%.

It was determined that employing the treated carbon blacks and anelastomer in an elastomeric composition of the present inventiongenerally resulted in poor abrasion resistance, compared to anelastomeric composition including the same elastomer and N234 carbonblack. However, as seen in Table 6, when Si-69 coupling agent wasincorporated into the composition, abrasion resistance returned toapproximately the same values as obtained with untreated carbon black.

As used herein, “untreated carbon black” means a carbon black preparedby a process similar to that used to prepare the corresponding treatedblack, but without the volatizable silicon compound and by makingsuitable adjustments to the process conditions to achieve a carbon blackwith an external surface area approximately equal to that of the treatedblack.

Example 6A

The dynamic hysteresis and abrasion properties of a black made byfollowing the procedure of Example 3A (and containing 1.91% Si) weremeasured as in Example 6. As seen in Table 6A below, tan δ at 70° C.values were reduced by 14%, tan δ at 0° C. values were reduced by 6% andthe wear resistance was reduced by 22%, for the SSBR samples whenTEOS-CB was substituted for N234. However, when Si69 coupling agent wasincorporated into the composition, the wear resistance for the TEOS-CBsample improved to 108% of the value for N234. The tan δ at 70° C.values decreased by 18% compared to N234 without coupling agent and 7%compared to N234 with coupling agent. The tan δ at 0° C. valuesdecreased by only 1.5% when the coupling agent was added to TEOS-CB,compared to N234 with coupling agent.

TABLR 6A Dynamic Hysteresis Data SSBR Abrasion @ Composition^(a) Si 69tan δ @ 0° C. tan δ @ 70° C. 14% Slip N234 0 0.428 0.184 100 N234 40.394 0.162 94 I#OS-CB 0 0.402 0.158 78 IEOS-CB 4. 0.388 0.151 108 ^(a)Cariflex S-1215; two stage mixing

Example 7

Improvement in Hysteresis by Three Stage Compounding

The beneficial properties obtained using the treated carbon blacks withthe elastomeric compounds of the present invention may be furtherenhanced by using an additional mixing stage during the compoundingprocess. The procedure for two stage mixing used in the previouscompounding examples, is described above in Example 4.

For three stage mixing, the stage 1 mixer was set at 80° C. and 60 rpm.After conditioning to 100° C. by heating the chamber with a dummymixture, the elastomer was introduced to the mixer at 100° C. andmasticated for one minute. The carbon black was added to the elastomerand mixing continued for an additional three minutes. In some cases, acoupling agent was also added with the carbon black, at a rate of 3 to 4parts per hundred of elastomer. The stage 1 masterbatch was then dumpedand passed through an open mill three times and stored at roomtemperature for 2 hours. The second stage chamber temperature was alsoset at 80° C. and 60 rpm. After conditioning to 100° C., the masterbatchwas introduced to the mixer, masticated for one minute, and theantioxidant was then added. At four minutes or when a temperature of160° C. is reached, the stage 2 masterbatch was dumped and passedthrough the open mill 3 times and stored at room temperature for 2hours. The third stage chamber temperature was set at 80° C. and 35 rpm.The masterbatch from stage 2 was then added to the mixer and masticatedfor 1 minute. The curing package was then added and the stage 3 materialwas dumped at 2 minutes and passed through an open mill 3 times.

Table 7 below compares hysteresis and abrasion characteristics forelastomers compounded with TEOS-CB using two and three stage mixing. Ascan be seen from the Table, three stage mixing results in higher tan δat 0° C. and lower tan δ at 70° C. Elastomeric compounds employing theelastomer set forth in Table 1A may be formulated by following theforegoing procedure.

TABLE 7 Dynamic Hysteresis Data - 2 Stage v. 3 Stage Mixing tan δ tan δabrasion at Carbon Black Si-69 at 0° C. at 70° C. 14% slip Duradene 715Two Stage Mixing N234 0 0.458 0.189 100 N234 3 0.439 0.170 103.5 TEOS-CB0 0.434 0.150 78.1 TEOS-CB 3 0.436 0.131 97.2 Duradene 715 Three StageMixing N234 0 0.471 0.165 100 N234 3 0.456 0.146 98.4 TEOS-CB 0 0.4460.139 57.6 TEOS-CB 3 0.461 0.113 101.8

Example 8

Oxidized Carbon Black

In another aspect of the present invention, it was determined by thepresent inventors that oxidation of the silicon-treated carbon black canlead to elastomeric compositions with enhanced hysteresis. For a blackmade using the conditions of Table 1, but with OMTS as the volatilizablesilicon-containing compound, and 2.74% silicon in the final black, theimprovement obtained with oxidation is illustrated in the followingTable. The hysteresis performance with the oxidized black is furtherenhanced by incorporating a coupling agent into the elastomericcompound.

The oxidized carbon black was prepared by treating the black with nitricacid. A small stainless steel drum was loaded with carbon black androtated. During rotation a 65% nitric acid solution is sprayed onto thecarbon black, until 15 parts per hundred carbon black had been added.After a soak period of 5 minutes, the drum was heated to about 80° C. toinitiate the oxidation reaction. During the oxidation reaction, thetemperature increased to about 100-120° C. This temperature was helduntil the reaction was completed. The treated black was then heated to200° C. to remove residual acid. The treated black was then driedovernight at 115° C. in a vacuum oven. Table 8 below compares hysteresischaracteristics for elastomers compounded with OMTS-CB and oxidizedOMTS-CB, with and without a coupling agent. Additional elastomericcompounds employing the elastomers set forth in Table 1A may beformulated by following the foregoing procedure.

TABLE 8 Dynamic Hysteresis Data - oxidized treated carbon black CarbonBlack tan δ tan δ Duradene 715 - 2 stage Si-69 at 0° C. at 70° C. N234 00.513 0.186 N234 3 0.463 0.176 OMTS-CB 0 0.501 0.166 OMTS-CB 3 0.4670.135 oxidized OMTS-CB 0 0.487 0.154 oxidized OMTS-CB 3 0.467 0.133

Example 9

Hysteresis and Abrasion Resistance for a Variety of Elastomers

Hysteresis and abrasion resistance was compared for elastomericcompounds prepared with treated carbon blacks compounded with differentelastomers, compounded with and without a coupling agent. Conventionalcarbon black was used as a control. The results are set forth in theTable 9 below.

These data show hysteresis improvement for all five elastomer systemstested. For example, the tan δ at 70° C. is reduced by between 10.5 and38.3% without a coupling agent, and by between 11.7 and 28.2% with acoupling agent, compared to the corresponding control.

It can also be seen that in all cases abrasion resistance for thetreated carbon black compound compared to the untreated controldecreases when no coupling agent is used. Abrasion resistance issubstantially improved when the coupling agent is used. It can also beseen that the hysteresis balance is improved with treated carbon black(with or without coupling agent), compared to control carbon black.

TABLE 9 Hysteresis and Abrasion Resistance - 3 Stage Mixing tan δ tan δwear at Carbon Black Si-69 at 0° C. at 70° C. 14% slip Solution SBR116/NS 114 −80/20 blend N234 0 0.689 0.151 100.0 N234 3 0.750 0.131123.1 TEOS-CB 0 0.721 0.115 86.3 TEOS-CB 3 0.751 0.094 115.4 SolutionSBR SL 574 N234 0 0.286 0.118 100.0 N234 3 0.260 0.108 96.4 TEOS-CB 00.246 0.101 58.0 TEOS-CB 3 0.258 0.093 86.8 Solution SBR PAT589 N234 00.676 0.190 100.0 N234 3 0.686 0.182 99.1 TEOS-CB 0 0.698 0.170 82.4TEOS-CB 3 0.726 0.150 134.2 Emulsion SBR 1500 N234 0 0.299 0.176 100.0N234 3 0.285 0.137 87.9 TEOS-CB 0 0.280 0.156 60.1 TEOS-CB 3 0.270 0.12188.1 Natural Rubber SMR 5 N234 0 0.253 0.128 100.0 N234 3 0.202 0.08885.8 TEOS-CB 0 0.190 0.079 60.9 TEOS-CB 3 0.173 0.069 88.6

Example 10

Cut Chip Resistance

A carbon black made as described earlier is used to make a truck-tiretread compound. The properties of the OMTS-CB are described in Table 10.The elastomeric composition is described in Table 11. The mixingprocedure is similar to Example 4 except that ZnO and Circo Light Oil(obtained from Natrochem Inc., Savannah, Ga.) were added with thestearic acid, anti-oxidants (Flexzone 7P® and AgeRite Resin D (obtainedfrom R.T. Vanderbilt Co., Norwalk, Conn.)) and the wax, SunproofImproved (obtained from Uniroyal Chemical Co., Middlebury, Conn.).

The tensile strength and elongation at break were measured using themethod described in ASTM D-412. The tearing strength was measured usingthe method described in ASTM D-624. As can be seen from Table 12,OMTS-CB gave a 19% improvement in tear strength, a 13% improvement inelongation at break, and a 36% reduction in tan δ at 70° C. atcomparable tensile strength. This shows that the cut-chip resistance andheat build-up properties are improved with OMTS-CB.

TABLE 10 OMTS-CB % Si in Carbon Black 4.62 DBP, cc/100 g 106.3 CDBP,cc/100 g 100.1 t-Area, m²/g 121.0

TABLE 11 Parts By Parts By INGREDIENT Weight Weight NR (5MR5) 100 100N234 50 — OMTS-CB — 50 Circo Light Oil 5.0 5.0 Zinc Oxide 5.0 5.0Stearic Acid 3.0 3.0 Flexzone 7P ® 1.5 1.5 AgeRite Resin D 1.5 1.5Sunproof Improved 1.5 1.5 Durax ® 1.2 1.2 Sulfur 1.8 1.8

TABLE 12 Tensile Elongation @ Tear Strength tan δ@ Strength, mPa Break,% Index, % 70° C. N234 27.2 552 100 0.133 OMTS-CB 26.9 624 119 0.086

Example 11

To evaluate the use of the silicon-treated carbon blacks of the presentinvention in a wire breaker compound, the following experiment wasconducted.

Nine compounds were prepared using N 326, N 231 and the OMTS-CBdescribed in the previous example. The analytical properties of thesecarbon blacks are described in Table 13.

TABLE 13 CARBON BLACK ANALYTICAL PROPERTIES N326 N231 OMTS-CB CTAB, m²/g81 108 125 DPB absorption, cc/100 g 72 92 104 CDBP, cc/100 g 67 86 101

Generally, heat build-up, as measured by tan δ at 60° C., and adhesion,increases with increase in surface area and structure.

The compound formulations are shown in Table 14. NR is SMR CV60(obtained from Malaysia). Silica is Hi-Sil 233 (obtained from PPGIndustries, Inc., Pittsburgh, Pa.). Naphthenic oil is a processing agent(obtained from Harwick Chemical Corporation, Akron, Ohio). Resorcinol isa bonding agent (obtained from Indspec Chemical, Pittsburgh, Pa.).Cobalt naphthenate is a bonding agent (Cobalt content 6%, obtained fromthe Shepard Chemical Co., Cincinnati, Ohio). Hexa ishexamethylenetetramine, a bonding agent (obtained from Harwick ChemicalCorporation, Akron, Ohio).

TABLE 14 Ingredients Parts Per Hundred NR 100 100 100 Carbon Black 55 5540 L Precipitated Silica — — 15 Napthenic Oil 5 5 5 ZnO 10 10 10 StearicAcid 2 2 2 Resorcinol — — 2.5 Hexa — — 1.6 Cobalt Naphthalene (6% Co) —2 — Santocure MDR 0.8 0.8 0.8 Sulfur 4 4 4

TABLE 15 BONDING AGENT M326 N231 OMTS-CB SYSTEMS* CTL Co HRH CTL Co HRHCTL Co HRH Tensile Strength, MPa 26.3 27.1 26.6 27.4 28.5 26.9 26.4 25.227.6 Elongation at Break, % 498 527 494 534 527 500 409 490 474Hardness, Shore A 67 67 74 71 71 78 65 70 74 Adhesion Strength, lb. 6895 45 94 106 45 90 107 91 Wire Adhesion G G F G G F G G F AppearanceRating** tan δ at 60° C. 0.137 0.145 0.116 0.166 0.170 0.133 0.134 0.1520.120 *Ctl-Control, without bonding agent, Co-cobalt containing bondingagent, HRH-silica-resorcinol-hexamethylene tetramine containing bondingagent. **G = good covering; F = fair covering.

In the experiment, a passenger tire steel cord wire, 2×2×0.25 mm, wascoated with a bran plate with 63.5% by weight copper. The adhesionrating was made using ASTM D-2229. This rating has two components: theforce required to remove the cord from the adhesion compound and theappearance of the removed wire. In general, the higher the forcerequired and the higher the rating of the appearance, the better theadhesion.

It is seen that the OMTS-CB shows the favorable heat build-up propertiesof N326 and at the same time the favorable adhesion properties of N231.

Example 12

Generally, in the production of carbon black, alkali metal saltadditives are used to control carbon black structure, for example CDBP.An increase in the amount of alkali metal salt added leads to a decreasein the structure of the carbon black. Two carbon blacks were made usingthe method described in Example 1. The conditions of manufacture were:

TABLE 16 CONDITIONS N234 TEOS-CB Air Rate, kscfh 12.8 12.8 Gas rate,kscfh 0.94 0.94 Feedstock Rate, lbs/hr 166 140.2 Si Compound Rate,lbs/hr 0 17 K+ Rate, gms/hr^(a) 0.547 0.604 ^(a) K⁺ injected as aPotassium Acetate solution.

The resultant carbon blacks were analyzed for surface area, structure,and silicon content. These values are set forth in Table 17 below.

TABLE 17 PROPERTIES N234 TEOS-CB % Silicon in Carbon Black 0.02 3.28CDBP, cc/100 g 103 110 t-area, m²/g 119.2 121.3 N₂-area, m²/g 122.7137.4

Thus, in this case the CDBP is found to increase by 7 points, eventhough the K+ rate is slightly higher in the reactor.

Example 13

Attachment of Organic Groups

OMTS-CB was made as described in Example 1, but having the followingproperties.

TABLE 18 % Silicon in Carbon Black 4.7 DBP, cc/100 g 103.2 CDBP, cc/100g 101.1 t-Area, m²/g 123 N₂ Area, m²/g 164.7

The carbon black was treated with 0.15 mmol of 4-aminodiphenyldisulfide(APDS) per gram of black to attach an organic group based on thepreferred procedure described earlier. The OMTS-CB was then compoundedaccording to the following formulation.

TABLE 19 Parts by Ingredient Weight Elastomer (Duradene 715) 75Elastomer (Tacktene 1203) 25 Carbon Black 75 Si-69 4.5 Oil (Sundex 8125)25 Zinc Oxide 3.5 Stearic Acid 2 Flexzone 7P ® 1.5 Sunproof Improved 1.5Durax ® 1.5 Vanax DPG 1 TMTD 0.4 Sulfur 1.4

Tacktene 1203 is an elastomer obtained from Polysar Rubber Corporation,Canada. Vanax DPG and tetramethyl thiuran disulfide TMTD) areaccelerators obtained from RT. Vanderbilt Co., Norwalk, Conn., andAkrochem Co., Akron, Ohio, respectively.

The mixing procedure described in Example 7 was used. The oil and Si-69were added in the first mixing stage. The performance of the compoundsis described in Table 20.

TABLE 20 tanδ @ tan δ @ Abrasion @ 0° C. 70° C. 14% Slip OMTS-CB 0.3850.158 100 OMTS-CB APDS 0.307 0.108 69

As shown in Table 20, attaching APDS to OMTS-CB results in a 31%reduction in tan δ @ 70° C. with a 20% reduction in tan δ @ 0° C.

Example 14

TABLE 21 A B C D E F Carbon Black Silicon Content (5%) 0 2.1 4.0 0 1.64.1 N₂SA t-area (m²/g) 54 52 54 54 51 52 DBPA (ml/100 g) 71 68 70 105 98102 Physical Properties Recipe 1 2 3 1 2 3 Hardness (Shore A) 66 65 6664 68 66 Tensile (MPa) 15.5 17.8 19.4 16.2 19.4 18.6 Elongation (%) 276271 300 255 265 276 Tear, Die C (kN/m) 23.6 24.2 25.4 22.9 24.3 26.3

TABLE 22 RECIPES Ingredient (Parts by Weight) 1 2 3 Royalene 509 EPDM100 100 100 AZO-66 Zinc Oxide 4 4 4 Hystrene Stearic Acid 1 1 1 CarbonBlack 60 60 60 Sunpar 2280 Paraffinic Oil 25 25 25 Rubbermakers Sulfur2.5 2.5 2.5 Methyl Tuads 1 1 1 Rhenogram MBT-75 (75% active) 2 2 2 Si-69Polysulfidic Silane 0 1.2 2.4 TOTALS 195.5 196.7 197.9 SUPPLIERS OFINGREDIENTS: Royalene 509 EPDM Uniroyal Chemical Co., CT AZO-66 ZincOxide Asarco, Inc., OH Hystrene Stearic Acid Hurnko Chemical Co., TNSunpar 2280 Paraffinic Oil Sun Refining and Marketing, PA RubbermakersSulfur R. B. Carroll, NJ Methyl Tuads R. T. Vanderbilt, CT RhenogranMBT-75 (75% active) Rhein-Chernie Corp., NJ Si-69 Polysulfidic SilaneStruktol, OH

As seen from the above EPDM examples, the use of silicon-treated carbonblack substantially improves tensile, elongation, and tear strength atcomparable hardness levels. These improvements in physical propertieswould provide advantages in useful lifetimes of seals, boots, andgeneral molded rubber parts. Similar advantages for the silicon-treatedcarbon blacks would be envisaged in peroxide cured elastomers which, forexample, do not contain unsaturated double bonds such as EPDM, or whichmay not need additional coupling agents to achieve their desirableproperties.

Advantages for the silicon-treated carbon blacks would also be expectedin elastomers containing elements other than carbon and hydrogen whichwould give additional interactions with the silicon-containing domainsin the carbon blacks. Examples of elastomers containing non-hydrocarbongroups would include but not be limited to NBR (acrylonitrile-butadienerubber), XNBR (carboxylic-acrylonitrile-butadiene rubber), HNBR(hydrogenated-acrylonitrile-butadiene rubber), CR (chloroprene rubber),ECO (ethylene oxide-chloromethyl oxirane), GPO (polypropyleneoxide-allyl glycidyl ether), PPO (polypropylene oxide), CSM(chloro-sulfonyl-polyethylene), CM (chloro-polyethylene), BIIR(bromo-isobutene-isoprene rubber), CIIR (chloro-isobutene-isoprenerubber), ACM (copolymers of ethyl or other acrylate and small amount ofvulcanizable co-monomer), and AEM (copolymers of ethyl or other acrylateand ethylene).

All patents, patent applications, test methods, and publicationsmentioned herein are incorporated by reference.

Many variations of the present invention will suggest themselves tothose skilled in the art in light of the above detailed disclosure. Forexample, the compositions of the present invention may include otherreinforcing agents, other fillers, oil extenders, antidegradants, andthe like. All such modifications are within the full intended scope ofthe claims.

What is claimed is:
 1. An elastomeric compound comprising an elastomerand an aggregate comprising a carbon phase and a silicon-containingspecies phase, wherein said aggregate imparts to the elastomer poorerabrasion resistance, comparable or higher loss tangent at lowtemperature and a lower loss tangent at high temperature, compared to anuntreated carbon black, and wherein said elastomer is: an oil-extendedderivative of one or more elastomers selected from styrene-butadienerubber, natural rubber, polybutadiene, and polyisoprene; or a co-polymerof a conjugated diene and an ethylenic group-containing monomer, whereinsaid monomer comprises one or more monomer selected from styrene,methylstyrene, chlorostyrene, acrylonitrile, 2-vinyl-pyridine, 5-methyl2-vinyl pyridine, 5-ethyl-2-vinyl-pyridine, 2-methyl-5-vinyl pyridine,alkyl-substituted acrylates, vinyl ketone, methyl isopropenyl ketone,methyl vinyl ether, alphamethylene carboxylic acids and the esters andamides thereof.
 2. The elastomeric compound of claim 1, wherein saidelastomer is a co-polymer of a conjugated diene and an ethylenicgroup-containing monomer, wherein said monomer comprises one or moremonomer selected from styrene, methylstyrene, chlorostyrene,acrylonitrile, 2-vinyl-pyridine, 5-methyl 2-vinyl pyridine,5-ethyl-2-vinyl-pyridine, 2-methyl-5-vinyl pyridine, alkyl-substitutedacrylates, vinyl ketone, methyl isopropenyl ketone, methyl vinyl ether,alphamethylene carboxylic acids and the esters and amides thereof. 3.The elastomeric compound of claim 2, wherein said ethylenicgroup-containing monomer comprises an acrylic acid or a dialkylacrylicacid amide.
 4. An elastomeric compound comprising an elastomer and anaggregate comprising a carbon phase and a silicon-containing speciesphase, wherein said aggregate imparts to the elastomer poorer abrasionresistance, comparable or higher loss tangent at low temperature and alower loss tangent at high temperature, compared to an untreated carbonblack, and wherein said elastomer is a chlorinated rubber or aco-polymer of ethylene and at least one olefin selected from propylene,butene-1, and pentene-1.
 5. The elastomeric compound of claim 4, whereinsaid elastomer is a chlorinated rubber.
 6. The elastomeric compound ofclaim 4, wherein said elastomer is a co-polymer of ethylene and at leastone olefin selected from propylene, butene-1, and pentene-1.
 7. Anelastomeric compound comprising an elastomer and an aggregate comprisinga carbon phase and a silicon-containing species phase, wherein saidaggregate imparts to the elastomer poorer abrasion resistance,comparable or higher loss tangent at low temperature and a lower losstangent at high temperature, compared to an untreated carbon black, andwherein said elastomer comprises at least one of the followingcomponents: ethylene propylene diene monomer (EPDM), wherein saidaggregate is present in an amount of from 50 to 250 parts per 100 partsby weight of said elastomer; poly(chloroprene), wherein said aggregateis present in an amount of from 10 to 150 parts per 100 parts by weightof said elastomer; natural rubber, wherein said aggregate is present inan amount of from 10 to 150 parts per 100 parts by weight of saidelastomer; hydrogenated nitrile butadiene rubber, wherein said aggregateis present in an amount of from 10 to 150 parts per 100 parts by weightof said elastomer; styrene butadiene rubber, wherein said aggregate ispresent in an amount of from 10 to 150 parts per 100 parts by weight ofsaid elastomer; and ethylene vinyl acetate, wherein said aggregate ispresent in an amount of from 10 to 150 parts per 100 parts by weight ofsaid elastomer.
 8. The elastomeric composition of claim 7, wherein saidelastomer is ethylene propylene diene monomer and said aggregate ispresent in an amount of from 100 to 200 parts per 100 parts by weight ofsaid elastomer.
 9. The elastomeric composition of claim 7, wherein saidelastomer is poly(chloroprene) and said aggregate is present in anamount of from 20 to 80 parts per 100 parts by weight of said elastomer.10. The elastomer composition of claim 7, wherein said elastomer isnatural rubber and said aggregate is present in an amount of from 20 to80 parts per 100 parts by weight of said elastomer.
 11. The elastomericcomposition of claim 7, wherein said elastomer is hydrogenated nitrilebutadiene rubber and said aggregate is present in an amount of from 20to 80 parts per 100 parts by weight of said elastomer.
 12. Theelastomeric composition of claim 7, wherein said elastomer is styrenebutadiene rubber and said aggregate is present in an amount of from 10to 150 parts per 100 parts by weight of said elastomer.
 13. Theelastomeric composition of claims 7, wherein said elastomer is ethylenevinyl acetate and said aggregate is present in an amount of from 10 to150 parts per 100 parts by weight of said elastomer.
 14. An article ofmanufacture formed from the elastomeric compound of claim 8, whereinsaid article is a weather strip, a hose, or an engine mount.
 15. Anarticle of manufacture formed from the elastomeric compound of claim 9,wherein said article is an engine mount, a seal, a hose, or a belt. 16.An article of manufacture formed from the elastomeric compound of claim10, wherein said article is an engine mount or a belt.
 17. An article ofmanufacture formed from the elastomeric compound of claim 11, whereinsaid article is an engine mount, a seal, a hose, or a belt.
 18. Anarticle of manufacture formed from the elastomeric compound of claim 12,wherein said article is a power belt, a conveyer belt, or a powertransmission belt.
 19. A hose formed from the elastomeric compound ofclaim 13.